The present invention relates to an electrochemical fine processing apparatus for electrochemically performing removal processing and addition processing of metal or polymer in a solution in order to produce a structure necessitating a high aspect ratio. It is especially used in a field in which the structure is manufactured using the micromachining technique.
One example of the conventional fine processing method is shown in FIGS. 3A-3D. This fine processing method uses photolithography represented by the semiconductor process (subtractive method). At first, a desired thin film 11 is formed on a substrate 10 made of silicon or the like using a sputtering method or a CVD method (FIG. 3A). Next, a resist pattern 12 is formed by spin coating or the like of a resist material, exposure of the resist material to a circuit structure pattern using a mask or an electron beam, and selective development of the resist material to leave the desired pattern 12 (FIG. 3B). Then, thin film 11 is selectively removed at regions not covered by resist pattern 12, using an etching liquid (FIG. 3C), and the remaining resist pattern 12 is removed to leave the thin film structure 13 (FIG. 3D).
In addition, in a fine processing method called the LIGA process, a photo-resist for X-ray is thickly coated on a substrate and is exposed to X-rays having strong linearity and strength generated from synchrotron radiation light. Thereby the resist can be formed deeply with a good pattern accuracy. Metal is formed on surface portions not covered with this pattern by means of electrocasting, and the resist is removed, whereby a structure having a high aspect ratio can be obtained.
However, in the conventional fine processing method, although a resolution of the order of sub-micron dimensions of the pattern can be achieved, it is difficult to perform film formation in the height direction, and it has been difficult to obtain a high aspect ratio. In addition, in the LIGA process, synchrotron equipment is necessary, which cannot be used easily and which creates the problem of increased cost.
Thus, there is also a method employing an electrochemical reaction in which a sample is allowed to approach a counter electrode with close distance, the sample being used as an acting electrode, and an addition electrode being used as the counter electrode, an electric current is allowed to flow between the addition electrode and the sample, whereby an electrochemical reaction is caused on the sample close to the addition electrode, so that metal or polymer is deposited on the sample. However, in such an electrochemical reaction method, as shown in FIG. 4, a high aspect ratio can be obtained, but the deposited substance 5 (metal and/or polymer) exhibits a film thickness distribution having no sharpness as shown in FIG. 4.